Download
polarity of molecules n.
Skip this Video
Loading SlideShow in 5 Seconds..
Polarity of Molecules PowerPoint Presentation
Download Presentation
Polarity of Molecules

Polarity of Molecules

884 Vues Download Presentation
Télécharger la présentation

Polarity of Molecules

- - - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

  1. Polarity of Molecules Revision Predicting Polarity Effects of Polarity

  2. Revision • Polarity is the simplified name we give to permanent dipoles (which also may be called permanent dipole – dipole interactions) • Polarity is caused when atoms of unequal electronegativity are covalently bonded together

  3. Predicting Polarity • Unfortunately its not so simple as saying if they’ve got different electronegativities then its going to be polar. We need to check a few other things first: • If it contains a metal it isn’t covalent so it doesn’t count • The two poles need to be exposed to the outside environment (i.e. if the d+ is exposed but the d- is hidden inside the molecule then it doesn’t have a dipole). Normally symmetrical molecules don’t have dipoles because of this

  4. Working It Out Look at the four molecules to the right. Which are polar? Explain your answers Note: Dotted lines indicate the bonds are travelling away from you, the bold one are towards you, the normal ones are on the plane of the paper

  5. Effects of Polarity • Polar molecules work like little magnets with each other. They will attract each other (and other charged particles). The results of this are: • They have relatively high melting and boiling points • They will dissolve some ionic compounds (if the force of the polar molecules is greater than the force of the ionic bonds) • They will dissolve other polar molecules

  6. Exam Practice - 2006 Can’t see the exam paper below? Go to the NCEA website and search for 90780 • Have a go at Questions:

  7. Exam Practice - 2007 Can’t see the exam paper below? Go to the NCEA website and search for 90780 • Have a go at Questions: